Adolescents are at considerable risk for becoming infected with HIV, and most HIV-infected adolescents acquire HIV via risky sexual behaviors. Alcohol consumption, substance use, childhood delinquency, criminality, and mental disorders have been found in many studies to be significant risk factors for sexual behaviors that increase risk of HIV infection among adolescents. However, developmental trajectories of HIV sexual risk behaviors and their relationship with other risk factors have not been well established because long-term prospective studies are relatively limited. Disentangling the complex associations of social and personal factors with HIV sexual risk behaviors requires systematic examination of patterns of HIV sexual risk behaviors over time and identification of factors that influence the change or continuity of these risky sexual behaviors. Drawing upon key concepts from problem-behavior theory (Jessor &Jessor 1977) and age-graded life- course theory (Sampson &Laub 1993), the proposed study seeks to provide a better understanding of the developmental trajectories of HIV sexual risk behaviors among adolescents as they transition from adolescence to young adulthood. Based on the National Longitudinal Survey of Youth, 1997 (NLSY97) covering years of 1997 to 2005, the proposed study will identify distinctive trajectory patterns of HIV sexual risk behaviors over a long observation period (e.g., approximately ages 15 to 25) and associated risk and protective factors at individual, family, school, peer, and community levels. We are particularly interested in how drug use, mental health problems, and criminality influence HIV sexual risk behaviors, as well as how trajectory patterns and risk and protective factors differ by gender or ethnicity/race. The specific aims of the proposed study are (1) to identify risk and protective factors (individual, family, school, peer, and community) associated with initiation and trajectories of HIV sexual risk behaviors;(2) to identify distinctive patterns of initiation and trajectories of HIV sexual risk behaviors;and (3) to describe gender and ethnic differences in the factors, processes and patterns resulting from the above aims. The NLSY97 data provide an excellent opportunity to investigate developmental trajectories of HIV sexual risk behaviors and their associations with drug use, mental health status, delinquency, and criminality among adolescents. Comprehensive data have been collected from a large nationally representative sample of youth since 1997 with multiple waves of assessments on sexual activity, drug use, mental health, delinquency, and criminality. Results of the proposed study will have implications for developing improved HIV prevention strategies for youths. PUBLIC HEALTH RELEVANCE: HIV is a significant public health problem. The proposed study seeks to provide a better understanding of the developmental trajectories of HIV sexual risk behaviors among adolescents who are observed over a long- period of time. Using longitudinal data from the National Longitudinal Survey of Youth, 1997 (NLSY97) covering 1997 to 2005, the proposed study will identify distinctive trajectory patterns of HIV sexual risk behaviors as these youths transition from adolescence to young adulthood and will examine how trajectories of risky sexual behavioral are influenced by drug use, mental health problems, and criminality. Results of the proposed study will have implications for developing improved HIV prevention strategies.